An Honest Look at “Light” vs. “Heavy” Training

Ever heard this one in the gym? “I’m just going easy today; yesterday was my ‘heavy’ day.” Those few words point to a plethora of misconceptions and false premises that thwart maximum muscle growth and can even lead to a loss of both strength and muscle mass.

It’s not that “light” or “heavy” are the right or wrong ways to train. It’s that you need to know exactly what you are trying to get out of your training in order to choose the right workout.

Your body responds to exercise in a similar way it responds to any other stress. It makes an adaptation so future stresses are less, well, stressful. For example, if you go out into bright sunshine today your light skin is pushed to the limits of its ability to protect you. It will adapt by darkening into a tan, so tomorrow the same amount of sunlight is less stressful to your body.

Similarly, you make muscle building progress by pushing your muscles to the limits of their ability to work. They adapt by increasing in size and power so the identical workout is less stressful next time.

The Invisible Line

The trick is finding the “invisible line” between a workout that is stressful enough to trigger new muscle growth and a workout that is not. We all understand that a day spent in the shade is not going to deepen our suntan, but do we truly understand that a “light day” of weight lifting will not increase our muscle? Because I assure you, it won’t.

To help visualize this very important and fundamental concept, imagine that your level of strength could be measured on a scale of 1 to 100. The number 100 represents the absolute limit of how strong you could become if everything possible was done perfectly to build your muscles.

Let’s say today your strength scores 35 on that scale. Now let us suppose that if you work your muscles to within 5 points of your maximum you will generate 2 points worth of new lean, hard muscle.

Now, it’s all very simple and clear. If today’s workout pushes past “30” in intensity of work done, then your strength level will grow to 37. Wow! A productive workout! But in your next workout you will have to push past “32” (5 points from your new maximum) in order to trigger even more muscle growth. If you do that “30” workout again, or, God forbid, a “light” day of say “18”, you don’t have a prayer of generating new muscle. So, what would be the point of the workout?

"You Can’t Train Heavy All the Time"

This leads us to something else you might have heard in the gym. “You can’t train heavy all the time.” I hear that refrain every time I try to explain the concept in the last paragraph. But what people really mean when they say that is, “I love to lift weights 3 or 4 days a week and I can’t train heavy that often.” Yes, very true. And I can’t get my hair cut 3 times a week just because I like going to the barber.

Reality check: Do you want to lift weights or do you want to build muscle?

The fact is you can’t train heavy all the time, but you can train heavy every time. But because your body needs time to recover from heavy, productive, muscle building exercise you need to add more time off between workouts. Our man in the above example can do a workout that is a 37…then one that is a 40…then one that is a 41, if he takes enough time off between workouts. That’s the way you work your way up to 100. That’s the way everyone has to do it. It’s a physiological law.

There is a concept that can really help unlock the secret to all of this: Perceived Effort. Hypothetically, if your level of strength is “28” then a “26” workout feels extremely intense and demanding. But if your strength level is “88” and you perform an “86” workout the perceived effort is identical! As you get stronger your workout intensity increases, but your perceived effort stays the same! That’s great news because it means you don’t really have to psych yourself for more and more difficult workouts…just the same level of perceived effort every time.

One Real Benefit of Light Training

You can see that the guy performing a “light day” is pretty much wasting his time. There is no possibility whatsoever that his light workout can trigger new muscle growth. In fact, if his last workout was productive his body will be in recovery mode and will need to fully recover before the new muscle growth will manifest. And doing another workout the next day – even a light one – will only slow down recovery.

Personally, I think the main reason guys go to the gym for “light workouts” is just so they can watch that cute blonde on the Stairmaster. The gym, for many guys, is what the local bar is for others: a place to meet and socialize. People have taken their psychological need for visiting the gym and rationalized it into a training method of frequent “light days” without regard to the physiological facts of the matter.

But, all that said, there is one tangible and valid benefit of lighter training. Stress relief. Speaking for myself, I tend to carry stress in the muscles of my lower back and my neck and traps. If I do a few deadlifts and shrugs I get instant relief. I only need to use 30 or 40 percent of my maximum to get this stress relieving benefit. The best part is that if I keep the perceived effort very low I know I’m not slowing down my recovery too much. The stress relief and mild endorphin release makes it a pretty good bargain. But I don’t kid myself that I’m building muscle. I know that takes truly grueling effort.

So, do you want to get the best of both worlds? Plan your productive, muscle building workouts far enough apart to ensure a steady climb to that “100” that represents your full genetic potential. And when you really need some stress relief and a shot of endorphins, you can do a few lifts at about 30% of your capacity without slowing down your overall progress too much.

Train with your brain,